/**
* author: Timothy Groves - http://www.brandspankingnew.net
* version: 1.0 - 2006-09-25
*
* requires: nothing
*
*/

var useBSNns;

if (useBSNns)
{
if (typeof(bsn) == "undefined")
bsn = {}
var _bsn = bsn;
}
else
{
var _bsn = this;
}



_bsn.Crossfader = function (divs, fadetime, delay )
{
this.nAct = -1;
this.aDivs = divs;

for (var i=0;i<divs.length;i++)
{
document.getElementById(divs[i]).style.opacity = 0;
document.getElementById(divs[i]).style.position = "absolute";
document.getElementById(divs[i]).style.filter = "alpha(opacity=0)";
document.getElementById(divs[i]).style.visibility = "hidden";
}

this.nDur = fadetime;
this.nDelay = delay;

this._newfade();
}


_bsn.Crossfader.prototype._newfade = function()
{
if (this.nID1)
clearInterval(this.nID1);

this.nOldAct = this.nAct;
this.nAct++;
if (!this.aDivs[this.nAct]) this.nAct = 0;
document.getElementById( this.aDivs[this.nAct] ).style.visibility = "visible";

this.nInt = 50;
this.nTime = 0;

var p=this;
this.nID2 = setInterval(function() { p._fade() }, this.nInt);
}


_bsn.Crossfader.prototype._fade = function()
{
this.nTime += this.nInt;

var op = this._easeInOut(this.nTime, 0, 1, this.nDur);
var ieop = op*100;
document.getElementById( this.aDivs[this.nAct] ).style.opacity = op;
document.getElementById( this.aDivs[this.nAct] ).style.filter = "alpha(opacity="+ieop+")";

if (this.nOldAct > -1)
{
document.getElementById( this.aDivs[this.nOldAct] ).style.opacity = 1 - op;
document.getElementById( this.aDivs[this.nOldAct] ).style.filter = "alpha(opacity="+(100 - ieop)+")";
}

if (this.nTime == this.nDur)
{
clearInterval( this.nID2 );

if (this.nOldAct > -1)
document.getElementById( this.aDivs[this.nOldAct] ).style.visibility = "hidden";

var p=this;
this.nID1 = setInterval(function() { p._newfade() }, this.nDelay);
}
}



_bsn.Crossfader.prototype._easeInOut = function(t,b,c,d)
{
return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}
